Power conversion system with galvanically isolated high frequency link

Abstract

A power conversion system has a three-phase AC input, where each AC input phase is linked to a string of cascaded single-phase AC-DC converters placed in series with a three-phase AC-DC converter. Each single-phase AC-DC converter in one embodiment includes a silicon carbide (SiC) pulse width modulated MOSFET H-bridge that placed in series with the three-phase AC-DC converter that includes a silicon (Si) SCR bridge. The single-phase AC-DC converters and the three-phase AC-DC converter together in one embodiment include a mixed silicon-carbide (SiC) and silicon (Si) device topology.

1. A power conversion system comprising a three-phase AC input, each AC input phase being linked to a string of cascaded single-phase H-bridge converters placed in series with a three-phase AC-DC converter. 
   
   
     2. The power conversion system according to  claim 1 , wherein each single-phase converter or three-phase converter comprises two-level or multi-level phase legs. 
   
   
     3. The power conversion system according to  claim 2 , wherein the multi-level phase legs are neutral point clamped or flying capacitor based. 
   
   
     4. The power conversion system according to  claim 1 , wherein DC outputs from the single-phase and three-phase AC-DC converters are coupled to modular DC-DC switch-mode converters with galvanic isolation. 
   
   
     5. The power conversion system according to  claim 4 , wherein outputs of the modular DC-DC switch-mode converters with galvanic isolation are connected to a common DC output bus. 
   
   
     6. The power conversion system according to  claim 5 , wherein the common DC output bus is connected to a DC-AC converter, such that the power conversion system serves as a transformer-like AC-AC converter with galvanic isolation. 
   
   
     7. The power conversion system according to  claim 5 , wherein the transformer-like AC-AC converter operates as a solid-state transformer or a power electronic transformer. 
   
   
     8. The power conversion system according to  claim 4 , wherein outputs of the modular DC-DC switch-mode converters with galvanic isolation are configured to provide multiple separately regulated DC outputs. 
   
   
     9. The power conversion system according to  claim 4 , wherein outputs of the modular DC-DC switch-mode converters with galvanic isolation are inverted to provide AC outputs. 
   
   
     10. The power conversion system according to  claim 2 , wherein outputs of the modular DC-DC switch-mode converters with galvanic isolation operate to provide multiple separately regulated DC outputs and single-phase or three-phase AC outputs at same or different frequencies to supply multiple load types. 
   
   
     11. The power conversion system according to  claim 1 , wherein the three-phase AC-DC converter comprises a passive rectifier bridge. 
   
   
     12. The power conversion system according to  claim 11 , wherein the passive rectifier bridge comprises a plurality of diodes. 
   
   
     13. The power conversion system according to  claim 11 , wherein the passive rectifier bridge comprises a plurality of silicon controlled rectifiers (SCRs). 
   
   
     14. The power conversion system according to  claim 13 , wherein SCRs in the passive rectifier bridge operate to limit inrush current during startup. 
   
   
     15. The power conversion system according to  claim 1 , wherein each single-phase AC-DC converter is configured to use pulse-width-modulated active rectification to allow control of its input AC current waveform. 
   
   
     16. The power conversion system according to  claim 1 , wherein any one of the single-phase AC-DC converters is bypassed or isolated at its AC input side for faults in the respective AC-DC converter or faults located downstream from the respective AC-DC converter, with controls of the remaining AC-DC converters within the string of AC-DC converters readjusted to allow continued power conversion system operation in the absence of the faulted AC-DC converter. 
   
   
     17. The power conversion system according to  claim 1 , wherein devices within the AC-DC converters comprise silicon semiconductors or silicon-carbide semiconductors configured for high frequency or high temperature operation. 
   
   
     18. The power conversion system according to  claim 1 , wherein the three-phase AC-DC converter is configured with active power devices to allow bidirectional power flow. 
   
   
     19. The power conversion system according to  claim 18 , wherein the active power device are configured within the cascaded single-phase H-bridge and in the three-phase bridge to switch at different frequencies to achieve a desired power quality and efficiency. 
   
   
     20. A power conversion system comprising a three-phase AC input, each AC input phase being linked to a string of cascaded single-phase AC-DC converters comprising a silicon carbide (SiC) pulse width modulated MOSFET H-bridge placed in series with a three-phase AC-DC converter comprising a silicon (Si) SCR bridge. 
   
   
     21. The power conversion system according to  claim 20 , wherein DC outputs from the single-phase and three-phase AC-DC converters are coupled to modular DC-DC switch-mode converters with galvanic isolation, and wherein the modular DC-DC switch-mode converters including rectifiers comprise a mixed SiC and Si device topology. 
   
   
     22. A power conversion system comprising a three-phase AC input, each AC input phase being linked to a string of cascaded single-phase AC-DC converters placed in series with a three-phase AC-DC converter, wherein the single-phase AC-DC converters and the three-phase AC-DC converter together comprise a mixed silicon-carbide (SiC) and silicon (Si) device topology. 
   
   
     23. The power conversion system according to  claim 22 , wherein DC outputs from the single-phase and three-phase AC-DC converters are coupled to modular DC-DC switch-mode converters with galvanic isolation, and wherein the modular DC-DC switch-mode converters including rectifiers comprise a mixed SiC and Si device topology.